Pebble flow control



April 10, 1956 c. E. ALLEMAN 2,741,547

PEBBLE FLOW CONTROL Filed May 1., 1950 FROM PEBBLE HEATER SYSTEMINVENTOR.

C. E ALLE MAN A TTORNE Y5 portion ofthe heating chamber.

United States Patent'fC V PEBBLE FLOW CONTROL Carl E. Allman, Etter,Tex,- assignor to Phillips PetroleiimCompanY, a corporation of BeiawareApplication May 1, BB, SerialNo. 159,359

14 Claims. (Cl. 23-28%) This-"invention relates to' apparatus andprocess for regulatingfiow of a contiguous flowable mass ofparticulate-solider In-one embodiment this invention relates to there'gulationof pebble flow through a pebble heater system.-

Various means have been proposed in the art for regulatin'g fio'w of'acontiguous flowable mass of particulate solids. Typical of suchwell-known means are those'involving screw conveyors, star valves, andsimilar devices utili'zing'continuously moving parts. Such devices :arenecessarily fabricated of special alloys offering the necessaryresistance to strong abrasive effects of the moving solids on the movingparts, and to provideresista'nce to wear from movement or" the parts.Such fabricating materials are costly and depreciate at a high rate andare "expensive to maintain. Furthermore, a temperature at which suchdevices can be operated is limited generallytoa level not higher thanfrom about 600 to800 F. by virtue of the increase in the amount'or"woman the moving parts incurred at those maximum permissibletemperatures. Another limitation' on the temperature at which suchdevices can be utilized -is the tensile strength of the material which,of course, decreases with increasing temperatures;

My invention is concerned with process and apparatus for controllingflow of a contiguous flowable particulate mass of solids, wherein nocontinuously moving equipment parts are required, and thefiowing'solidscanbe handled'at temperatures as high asfrom 800 to 1200"F. or higher: My invention further provides for the use or" more readilyavailable and relatively'inexpensive fabricating :materialsincontrolling such solids flow than'can housed in the construction of asolids fiow'controller involving the use of continuously moving parts."

Although my invention is well applied to the regulation ofthe rat'e' ofnew of -a flowable comi uous particulate mass-'ofsolids'through a solidssystem ofany kind, it is particularly advantageous as applied to thecontrol of fiow of such-solids while-at a temperatureas' high" as frOmSOO to 1200 F., and'in many instance's' high'er. Accordingly, I haveapplied my invention in a preferred embodiment to the-control ofpebbleflow'thr'oug h a pebble heater system, wherein in many instancesit-is: advantageous to regulate the pebble flow 'while handlingflowing-pebbles at'temperatures as high as from 800 to 1200' F.or'higher;

A pebble heater' system, or pebble heater apparatus I chamber. Acombustion zone; or chamber, is positioned adjacent or in closeproximity to the sides'of the -lower Thetop ,or upper zone is Combustiongas from r 2,741,547 Patented Apr. 10, 1956 2; E a 'corn'bustion chambris passed through the mass of pebbles inthe' pebble-he'ating chamber. Ahot' ga'ssource other thaira combustion-means is sometimes employed.-

A contiguous mass of particulate contact material, often referredtoaspebbles, fills the pebble heating zone, the interconnecting zone -01"-throat,--and 'the gas reaction 'or heating 'zon'efand' ilo'wsdownwardly through these zones by gravity. Pebbles are discharged' from'the 'bottom' of the gas-reaction zone at a controlled rate, and'returned, usually-,by'elevating means, to-theinlet in the upperporitionof the -pebble heating zone; A'contiguous moving pebble massthereby fills the pebble heating zoney-gas heating zone, and theinterconnecting zone', on th'ro'at, at all times.

The term pebbles, as usedthroughout the-specification, denotes any solidrefractorymaterial offlowable form and size that can :be utilized tocarry heat-from one zone :to another. Pebbles'are"preferablysubstantially spherical and about & inch to 1 inch in diameter; thepreferred range being about fis inch-t0 /2 inch; Pebbles arefo'rmed of arefractory material which will withstand temperatures at-least' as-highas the' highest temperature attained in the pebble "heating:chamber, and must be capable also of withstanding temperaturechanges-within the apparatus. Refractory materials such as metal alloys,ceramics; or other satisfactory =material may .be utilized toform'suchmaterialsn Siiiconcarbide, alumina, peri clase, thoria,beryllia,'.Stellite, zirconia, and mullite may be satisfactorily used-to form 'such'pebblesor may be used'in admixture-with each other orwith other materials. Pebbles-formed of such materials, when properly:fired, ser ve veryrwell at high temperatures. Some pebbles, such asmullite-alurnina-pebbies;-Withstand temperatures up to" about 3500 F;Pebbles :which'are used may be either inertor catalytic, asused'inanyselected process.

Pebble heater apparatus is generally :employed in :the thermal treatmentor conversion. of reactant materials, often hydrocarbons." Operation ofsuch'a pebble-system generallydnvo'lv'e'scirculating. a contiguouspebble mass through-the 'pebble heating chamber; interconnectingithroatand reaction'chamb'er. That portion ofthe pebble mass descending throughthe heating-chamber is heated to .a suitable predetermined temperatureabove a desired treating or conversion temperature in heat exchangerelation with combustion gas or other 'hot gases from any desiredsource. Pebbles are often heated in the-whe'at-ing';chamber totemperatures ashigh as froni 2,000 t0'3,000 Fz, andinsomecaseshighen-dependent upon the teinperature requirements of thesubsequent 'masshaving-given up -heat to the material treatedwin thetreating zone, descends-through the bottom of the reaction chamberan'dis fed to an elevator for further handling, generally foriransfer toan inlet atxthe top of the pebble heating :chamber for reheating andrecirculation through the system An object of mypinventionis toprovideprocess and apparatusafor regulating flow'of a contiguous flowableparticulate mass: of solids Another object is to provide apparatus forregulating fiow of a flowablecontiguous mass ofparticulatesolids whileat a temperature as -high as 1200" F. or higher.

Another object is to provide: apparatus free of=con tinuou'sly'movingiparts tor-regulating the fiow of a contiguous flowable mass ofparticulate solids.

Anotherobject is I to provide process: and A apparatus for controlling;th'e fiow of pebbles;-through. a'-pebble heater system: I

' discussed above.

communication at its other end with asource of a con-- tiguous mass offlowable particulate solids; and a fluent solids outlet conduitextending downwardly from a point inside the reservoir intermediate apoint inside a zone defined hereafter and a point outside that zone,to'a point outside the reservoir. The zone portion above referred to isan imaginary cone based on the horizontal, having the outlet end of thesolids inlet conduit at'its apex and having an apex angle generallywithin the limits offrom about 90 to 140, although in most instanceswithin a narrower range of 100 to 130. The value of the apex angle isnot unconditionally within the limits above specified, but is dependentupon the size, shape, surface, and the like, of the solid particlesbeing handled, as discussed in more detail hereafter. The upper end ofthe outlet conduit is out of vertical alignment with the outlet end ofthe solids inlet conduit. Either or both, of these conduits, as desired,are adjustably movable to regulate the position of the outlet conduitwith respect to disposing its upper end at a predetermined pointintermediate the points respectively inside and outside the imaginaryzone In a broad embodiment of the process of my invention, a stream ofcontiguous fiowable particulate solids is passed into the solidsreservoir through the solids inlet'couduit. A solids mass isgravitationally formed in the reservoir and tends to assume the shape ofa horizontally based cone having the outlet end of the solids inletconduit at its apex. The size of the apex angle is dependent on theangle of repose of the solids mass in the reservoir, i. e. the angleformed between the upper surface of the solids mass and the horizontal,above which the solids will not flow from the solids inlet into thereservoir gravitationally, but below which solids flow by gravityfromthe downstream end of the solidszinlet conduitinto the reservoir.Usually the angle of repose for a contiguous mass of solids is withinthe limits of from about 20 to 45 dependent on the shape, size, andsurface characteristics of the solid particles. Obviously, the greaterthe size and the more irregular the shape and surface of the solidparticles, the

greater the angle of repose, and conversely the smaller the particlesize and the more regular the shape and surface characteristics of theparticles, the less the value of that angle. 7

When the position of either or both conduits is regulated as abovedescribed, the position of the upper end of the outlet conduit isaccordingly altered with respect to the surface of the solids mass inthereservoin. When the inlet conduit is extended downwardly while theoutlet conduit is stationary the surface of the solids mass in thereservoir is lowered and theupper end of the outlet con duit is inefiect raised, and conversely, if the inlet conduit is raised, theheight of the pebble-mass is increased and the upper end of the outletconduit is in effect lowered. When the outlet conduit is adjustablymoved in a downward or upward direction, its upper end will, of course,be disposed accordingly with respect to the surface of the solids mass.Obviously then, one of these conduits can be adjustably moved with theother fixed, or both can be moved at the same time to dispose the upperend of the outlet conduit at a predetermined point with respect to thesurface of the solids mass in the reservoir- Also, it is obvious thatthe position of the upper end of the outlet conduit, with respect tothelower end of the inlet conduit, will be varied as the respectiveconduits are raised or lowered. Y

When the upper end of the outlet conduit is above th surface of thesolids mass, no solids flow can occur. As

the position of the outlet conduit is lowered, with respect to thesurface of the solids (by moving either conduit),

a point is reached at which some solids can roll into the the conduit,solids flow will occur at a certain rate for any given position of theconduits. Solids will flow at a higher rate as the relative position ofthe outlet conduit is lowered. Ultimately, the position of the outletconduit, relative to the end of the inlet conduit and the surface of thesolids, can be such that the outlet conduit is flowing solids full andno further increase in flow rate is possible. Such a position is reachedwhen the upper end of the outlet conduit is well below the surface ofthe solids mass and directly, or nearly directly, below the lower end ofthe inlet conduit.

The accompanying drawings illustrate preferred forms of apparatus andprocess of my invention, and'are discussed with reference to controllinga flow of pebbles. It is to be understood, however, that my invention isalso well applied to the control of flow of contiguous flowable solidparticulate materials of any type, and-that various modifications of theillustrated process and apparatus can be made and still remain withinthe scope of my invention.

Figure l is a transverse sectional view of an apparatus embodying myinvention wherein both the inlet and outlet conduits are verticallydisposed in the solids reservoir and offset from each other. Figure 2 isa sectional View similar to that of Figure 1, except that the inlet andoutlet conduits are not necessarily vertically disposed. Figures 3A,318, 4A, and 4B illustrate modified forms of the outlet conduit ofFigures 1 and 2 that can be utilized. Figure 5 is illustrative ofapparatus of my invention as applied to controlling a flow of pebblesthrough a pebble heater system.

Referring to Figure 1, pebble inlet conduit 10 extends verticallydownward through sleeve 11 into pebble reservoir 12, and is incommunication at its upper end with pebbles in a pebble heater system.Conduit 10 is axially adjustable and can be moved in an axial directionthrough sleeve 11 by means of rack and pinion means 13. Conduit 1i)terminates in reservoir 12 to admit pebbles to form pebble mass 14having a conical upper surface with the outlet end of conduit ltl at theapex and an apex angle within the limits of about 99 to 140, dependentupon the size, shape, and surface characteristics of the pebblestherein. In most instances the angle of repose of the pebbles lieswithin a range of from 25 to 40 and thus the apex angle will generallybe within the limits of from to Outlet conduit 16 is vertically disposedand extends into reservoir 12 through sleeve 17 and is axiallyadjustable. Conduit 16 can be moved in an axial direction through sleeve17 by means of rack andpinion means 18. The upper end 19 of conduit 16can be disposed completely within pebble mass 14, i. e. below surface20, in which case flow of pebbles through conduit 16 is substantiallyunrestricted, or it can be disposed completely above surface 20, inwhich case pebble flow from mass 14 into conduit 16 is completelyterminated. When end 19 is disposed so that a portion of itscross-sectional area is within mass 14 and the remaining portion is inspace 21, a proportionate degree of flow of pebbles from mass 14 intoconduit 16 is effected. In other words, depending upon the proportion ofthe cross-sectional area of upper end 19 of conduit 16 in theregion'where pebble flow can occur, the rate of flow of pebbles intoconduit. 16 can be regulated. After the selected rate of pebble flow isestablished the position of conduit 16, with respect to pebble mass 14,is not disturbed and the flow continues at the predetermined rate overany desired operating period without the need for any moving equipmentparts of any kind.

As shown in Figure 1, both conduits 10 and 16 are movably adjustable inan axial direction. It is to be understood, however, that although bothconduits canbe sea-1 ,254?

moved in "an axial direction when determining: the final positionpfupper 'end 12 0f conduit 16 "with? respect to the surface 20" ofpebblemass 14,1 prefer generallyto maintain oneof'thse conduits in afixed position a-nd to axially move the other conduit with respect tothat fixed position." Accordingly; in one embodimentyconduitm is rigidlyattached to reservoir12 and conduit 16 is axially movable as shown;and-inanotherembodiment the-converse-is true,'i; e. conduit 16 isrigidly disposed and con duit 111 is axially'adjustable.

As" illustrated "in Figure 2, it is not necessarythat conduits 10ancl"16"be' each vertically'disposed.- Con duit 10 can extend intoreservoir 12 at"an'y desired angle', theten'd'eney"of"mass 14 to form ahorizontally based cone with pebble inlet conduit 10 at'itsapex"being'thesa'me regardless of the anglefat which 'conduit 10 isdisposed. Similarlyjconduit 16 is not necessarily vertically disposed;but'can be disposed downwardly from the interior of"zone"'12 atany-desiredangle. However, in orderforth'efull capacity of conduit 16 tobe utilized in conducting pebble flow, it must be disposed at an anglewith the horizontal greater than about 40", since it "has been foundthat such a conduit disposed'at a smaller angle cannot carry full pebble'fiow." In-any case," the inlet end 19 *of'outlet' conduit 15 is"adapted to'be'disposed out of'vertical" alignment with the outlet end9of 'inletcondu'it 10.- Expressed in another manner; th'e lo'ngitu'dinalaxis'of conduit 16' is ou'tof vertical alignment'with theoutletend 9 ofconduit-10 I prefer'to employ a single conduit 16 having acrosssectional area substantially the same as that of conduit 10, sothat v/he'n conduit 16 is axially moved to dispose its upper end: 19completely within the pebble mass 14, substantially unrestricted flow ofpebbles will occur from conduit lll. Howeverg-itdesired, a finer controlof flow conduit 10-carr'be eflected byfemploy'ing" a -plurality ofconduits 16 "having a'total cross-sectional area as' desired; butpreferably about thesame as that" "of conduiewf" In this-manner anyinherent manipulative error can be substantially reduced in controllingthe pebble flow rate.

Asillu'str'ated in Figures 3a and 3b,-'the end 196i conduit 16 can bebeveled to permit a larger proportion of its area to be available topebbles in the region where pebble fiow--ca'n occu'ryther'eby increasingto a :si'gnificantde gree 'the' "accuracy in adjusting the position-ofupper end 19 with respect to surface 20 of pebble ma's's 14' "td"establish the desired rate of lpebble' flow from conduit 10. As"illustrated 'in these figures, the beveled end portion can directly facethe flowing pebbles or it can be disposed at an angle to the line ofsuch pebble flow. Similarly, Figures 4a and 4b further illustrate theapparatus embodiment of my invention wherein the upper end 19 of conduit16 is beveled.

With reference to Figure 5, pebble heater apparatus 22 consists ofpebble heating chamber 23, gas reaction chamber 24, throat 26interconnecting chambers 23 and 24, pebble outlet conduit 27, pebbleinlet conduit 28, pebble elevating means 29, inlet conduit 31 foradmitting combustible gases into combustion chamber 32, flue gas outlet33, reactant gas inlet 34, and product gas outlet 36. Pebble inletconduit 10 of pebble flow controller 37 is axially disposed with conduit27 and in communication with pebbles passed through the bottom ofchamber 24 into conduit 27. Conduits 10 and 16 extend into reservoir 12in any manner, as discussed hereinabove with respect to Figures 1, 2,3a, 3b, 4a, and 4b. Conduit 16 is connected with elevator inlet conduit33 for discharge of pebbles from pebble mass 14 in reservoir 12, intoelevator 29, whereby the pebbles discharged through line 16 are recycledto the pebble heater system for recirculation.

In the operation of the embodiment illustrated in Figure 5, acombustible gas mixture is introduced through line 31 into"comhustionschambfi sz;iand bumed thereinto provid'e a -combustion:temperature generally a; as high 'as' about 2,000 to 3,069 Fior higheraConibus tion ga's thus formed is?passed -upwardly through? chantbet- 23in heat exchanged'elationwvitlr a' downwardly-flow ing contiguous m'ass'of pebbles'therein to heat same to a temperature above aipredet'ermined" conversion tern-'- peratute. Combustion gases having:imp'arted heat to pebbles in chamber 23', are withdrawn-through conduit33. The heated-'pebble mass fiowingdownwardly through throat 26 ispassed: through reaction chamber 24 in counter-current flow and hea'texchange firelat-ion withs a reactant gast'ofteria hydrocarbon,-introduced into cham her 24- through cotiduit 34, whereby thereactarit'is heated to the 'conver'sion temperamre and conversionproduct-isformed; Conversion productis-withdrawn from chamber '24through conduit -36. Pbbles: having imparted heat to'-' thereactant-materials are discharged from chamber 24: through-line 27: intoinlet con'duitll) of-pebble flow cor'itr'oller 37;

In pebble heater operati'ong itisgenerally necessary that thetemperature- 0f: the"pebbles' 'clischarged'-be not abov'e'a maxirtiilrn-often from 500 to 800' F, for-the reason that the controllerm'e'ansis'notoperable for long periods when "utilized -fo"rhandling1ipebbles athigher temperatures, as discussedhereinabove." Howeveryitis oftenadvantageou's that the temp'eratu're ofthe pebbles dischar ed'fronft---charnbe r 24"beliigher than 800" F;, and often 'ashigh as'1200 1 .,"deperld'ent upon the specific conversionprocess conducted inpebble heater system 22,as for example: in cra'cking li'ght hydrocarbon'gases such as'- ethane or propane; I Ais provided' for 1 by my invention', the temperature of pebbles intro'ducedinto pebble reservoir I12 from? conduit llfartd: dischargedthrough line-16 cm be considerabiyhigher than the-800- F. limit discussed hereabdve; being a's-highas="12-00' F1; or higher when desired.= This is possibl'e to alarge 'extent because the fabric'a ting' nnaterials of controller 37 canbe highly insulated or can be completely-ceramic,- thus providingforthehandling. of pebbles at temperatures fa'r exceeding" l20G-"- F.=,and'tor'the further-reason that there are no continuously moving partsinvolved' in the structure of flow controller-'37.-

Therate bf fi'ow of pebbles:- throug'h pebble heater system 22 isregulated by controller 37-" at-a predetermined" constant level tor overany desiredoperating period without interruption 'of any -kiud1- As-willbe-evident-to those skilledin the-art, various modificationscan be' madeor -followed, 111 1116 light-0t the foregoing disclosure and discussion,without departing from the spirit or scope of the disclosure or from thescope of the claims.

I claim:

1. Apparatus for regulating the flow of pebbles through a pebble heatersystem, comprising a pebble chamber, said chamber being completelyclosed except for a pebble inlet conduit and a pebble outlet conduittherefor; said pebble inlet conduit extending downwardly into saidchamber and terminating therein; a pebble mass in said chamber having aconical upper surface and having its apex at the lower end of said inletconduit; said pebble outlet conduit extending downwardly from theinterior of said chamber to an external point and having its upper endout of vertical alignment with the terminated end of said inlet conduit;at least one of said conduits being longitudinally movable; and meansfor longitudinally moving such a conduit so as to dispose the upper endof said outlet conduit at a predetermined point intermediate a point insaid mass and a point in said chamber above the upper surface of saidmass.

2. An improved pebble heater apparatus, comprising a pebble heatingchamber; a reaction chamber positioned below said heating chamber; apebble throat conduit interconnecting said heating chamber and saidreaction chamber; said chambers and said throat containing a contiguousmass of pebbles; means for introducing hot heat exchange gases incontact with pebbles in said heating chamberg pebble inlet'means in anupper portion of said heating chamber; gas outlet means in an upperportion of said heating chamber; gas inlet means and efiiuent gas outletmeans in said reaction chamber; a pebble receiving chamber below'saidreaction chamber, said receiving chamber being completely closedexcept for a pebble inlet conduit and a pebble outlet conduit therefor;said pebble inlet conduit extending down wardly into said receivingchamber so as to convey gravitational flow of pebbles from said reactionchamber into said receiving chamber; a pebble mass in said receivingchamber contiguous with pebbles in said reaction chamber, and having aconical upper surface and its apex at the lower end of said inletconduit; said pebble outlet conduit extending downwardly from theinterior of said chamber to an external point and having its upper endout of vertical alignment with the outlet end of said inlet conduit; atleast one of said pebble inlet and pebble outlet conduits beinglongitudinally movable; and means for longitudinally moving such alongitudinally movable conduit so asyto dispose the upper end of saidoutlet conduit at a point intermediate a predeten mined point in saidmass and a point in said chamber above the upper surfaceof said mass.

3. A process for regulating flow of pebbles through a pebble heatersystem, comprising gravitating a stream of pebbles from such a systeminto a pebble receiving zone through a first conduit extendingdownwardly into said zone, and forming a pebble mass therein contiguouswith pebbles in said pebble heater system, conveying by gravitationalfiow only, pebbles from said mass through a second conduit extendinginto said mass and downwardly away from saidreceiving zone and spacedout of vertical alignment with said first conduit, and controlling therate of gravitational flow of said pebbles by varying the degree towhich said second conduit extends into said mass.

4. The process of claim 3 wherein said gravitational how of pebbles isconveyed in a lateral direction from said pebble mass.

5. The process of claim 3 wherein said gravitational flow is conductedin a substantially vertical direction from said pebble mass.

6. The process of claim 3 wherein said rate of gravitational flow ofpebbles is controlled by varying the proportion of the area of the upperend of said second conduit in contact with pebbles flowing from saidmass.

7. A process for regulating flow of fiuent solids through a solidshandling system, comprising gravitating a stream of solids from such asystem into a solidsreceiving zone through a first conduit extendingdownward- 1y into said zone and forming a solids mass therein contiguouswith solids in said solids system, conveying by gravitational flow only,solids from said solids mass through a second conduit extending intosaid mass'and downwardly away from said receiving zone and spaced out ofvertical alignment with said first conduit, and controlling the rate ofgravitational how of saidsolids by varying the degree to which saidsecond conduit extends into said mass.

8. Apparatus of claim 1 wherein only said inlet con duit islongitudinally movable.

9. Apparatus of claim 1 wherein only said outlet conduit islongitudinally movable.

10. Apparatus of claim 1 wherein both said inlet and outlet conduits arelongitudinally movable.

11. The apparatus of claim 1 wherein each said .conduit is verticallydisposed. i

12. The apparatus of claim 1 wherein said upper end of the outletconduit is cut at an angle other than per: pendicular to the axisthereof.

13. The apparatus of claim 1 wherein said inlet conduit is verticallydisposed and said outlet conduit is disposed angularly through a sidewall of said chamber.

14. The apparatus of claim 1 wherein one of said conduits is adjustablysecured to said chamber, and 'the other of said conduits is rigidlysecured to said chamber.

References Cited in the tile of this patent UNITED STATES PATENTSToggart: Handbook of Mineral Dressing, 1945, John Wiley and Sons, Inc.,N. Y. C., publishers, page 23, of section 11. I

Perry: Chemical Engineers Handbook, 1950, McGraw- Hill Inc., N. Y, C.,publishers, pages 600 and 940, p

1. APPARATUS FOR REGULATING THE FLOW OF PEBBLES THROUGH A PEBBLE HEATERSYSTEM, COMPRISING A PEBBLE CHAMBER, SAID CHAMBER BEING COMPLETELYCLOSED EXCEPT FOR A PEBBLE INLET CONDUIT AND A PEBBLE OUTLET CONDUITTHEREFOR; SAID PEBBLE INLET CONDUIT EXTENDING DOWNWARDLY INTO SAIDCHAMBER AND TERMINATING THEREIN; A PEBBLE MASS IN SAID CHAMBER HAVING ACONICAL UPPER SURFACE AND HAVING ITS APEX AT THE LOWER END OF SAID INLETCONDUIT; SAID PEBBLE OUTLET CONDUIT EXTENDING DOWNWARDLY FROM THEINTERIOR OF SAID CHAMBER TO AN EXTERNAL POINT AND HAVING ITS UPPER ENDOUT OF VERTICAL ALIGNMENT WITH THE TERMINATED END OF SAID INLET CONDUIT;AT LEAST ONE OF SAID CONDUITS BEING LONGITUDINALLY MOVABLE; AND MEANSFOR LONGITUDINALLY MOVING SUCH A CONDUIT SO AS TO DISPOSE THE UPPER ENDOF SAID OUTLET CONDUIT AT A PREDETERMINED POINT INTERMEDIATE A POINT INSAID MASS AND A POINT IN SAID CHAMBER ABOVE THE UPPER SURFACE OF SAIDMASS.